Electromagnetic relay

ABSTRACT

In an electromagnetic relay in which a contact mechanism 50 provided on a base 10 is driven by a card 60 which slides and moves in parallel to the axis of an electromagnet block 20 provided in the base 10 as the electromagnet block 20 is magnetized and demagnetized, the base 10 comprises a guide portion 17 for restricting the card 60 in its position. This prevents variations in the performance characteristics so that high productivity and long service life of contacts can be obtained.

TECHNICAL FIELD

The present invention relates to an electromagnetic relay superior ininsulating characteristic and, more particularly, to its card supportingstructure and contact mechanism.

BACKGROUND ART

An electromagnetic relay superior in insulating characteristic accordingto the prior art is shown in FIGS. 25 and 26 as an example.

In this electromagnetic relay, a cylindrical frame 1a with one sideclosed is formed integrally with a base 1 at a generally central portionof the base 1. Into a cavity 1b of the cylindrical frame 1a, anelectromagnet block 2 to which a moving core 3 is assembled rockable viaa hinge spring 4 is inserted sideways along the axial direction, whilefixed contact terminals 5, 6 and a movable contact terminal 7 areinserted and fixed sideways. Then, a pair of elastic arms 8a, 8aprovided at one end of a card 8 are engaged with engagement recesses 3a,3a of the moving core 3, while a pair of projections 8b, 8b provided atthe other end of the card 8 are engaged and assembled with engagementrecesses 7d, 7d of an elastic contact member 7c forming the movablecontact terminal 7. In this way, the card 8 is supported so as to bereciprocatingly movable in parallel to the axial direction of theelectromagnet block 2. In addition, reference numeral 9 denotes a casingfittable to the base 1, and the contact terminals 5, 6 and the movablecontact terminal 7 have fixed contacts 5b, 6b and a movable contact 7b,respectively, provided at high locations away from their terminalportions 5a, 6a and terminal portion 7a.

When the moving core 3 rocks by its being attracted to or separated froman iron core 2a of the electromagnet block 2 with the electromagnetblock 2 energized or de-energized, the card 8 resultantly movesreciprocatingly so that the other end 8c thereof presses and releasesthe top end portion of the elastic contact member 7c. As a result, themovable contact 7b contacts and separates from the fixed contacts 5b,6b, alternately, whereby the circuit is opened and closed.

However, the electromagnetic relay according to the prior art has thefollowing three technical problems.

As a first technical problem, according to the prior art electromagneticrelay, the assembly of the card 8 to the movable contact terminal 7involves a process of forcedly bending the elastic contact member 7coutward.

This would cause the elastic contact member 7c to undergo some plasticdeformation, which would often incur variations in performancecharacteristics.

Also, the aforementioned electromagnetic relay involves many assemblingoperations so that it takes time and labor for the card 8 to beassembled to the elastic contact member 7c, resulting in lowproductivity.

Further, in the aforementioned electromagnetic relay, not only thedrive-use projection 8c presses the elastic contact member 7c, but alsoa pair of the projections 8b, 8b are engaged with the engagementrecesses 7d, 7d of the elastic contact member 7c. Therefore, variationsin the assembly precision would make it likely that the drive-useprojection 8c makes skew contact with the elastic contact member 7c asthe card 8 moves reciprocatingly. This leads to a problem that themovable contact 7b of the movable contact terminal 7 makes nonuniformcontact with the fixed contacts 5b, 6b of the fixed contact terminals 5,6 such that the fixed contacts 5b, 6b are accelerated to wear andshortened in service life.

In the light of the aforementioned first technical problem, a firstobject of the present invention is to provide an electromagnetic relaywhich is free from variations in performance characteristics, high inproductivity, and long in contact service life.

As a second technical problem, according to the prior artelectromagnetic relay, the electromagnet block 2 is inserted sidewaysalong the axial direction into the cavity 1b of the frame 1a provided inthe base 1, wherein ahead in the insertion direction, arranged are thefixed contacts 5b, 6b and the movable contact 7b partitioned by theframe 1a. Therefore, whereas the assembly precision of the electromagnetblock 2 with respect to the base 1 directly affects the move extent ofthe card 8, there is a difficulty in assembling the electromagnet block2 to the base 1 with high precision, such that variations in theperformance characteristics often occur.

Also, the base 1 needs to be molded integrally with the frame 1a, andtherefore has a complex configuration. This makes the molding processdifficult as well as the manufacture of the mold also difficult.

Further, the electromagnet block 2 needs to be inserted into the base 1sideways along the axial direction, a direction other than that in whichthe other components are assembled. As a result, the automaticassembling machines become complex to arrange in the assembly line,which leads to a problem that the automatization of assembly processesdemands more tasks.

In the light of the aforementioned second technical problem, a secondobject of the present invention is to provide an electromagnetic relaywhich is free from variations in performance characteristics, and whichallows easy accomplishment of required molding work, manufacture ofmolds, and automatization of assembly.

As a third technical problem, according to the prior art electromagneticrelay, since the fixed contacts 5b, 6b and the movable contact 7b arelocated at high positions away from the top surface of the base 1, thefixed contacts 5b, 6b and the movable contact 7b may result in largedeflections even when the fixed contact terminals 5, 6 and the movablecontact terminal 7 are slightly inclined by thermal deformation of thebase 1 due to elevated outside temperature. Therefore, the performancecharacteristics tend to vary due to shifts of the fixed contacts 5b, 6band the movable contact 7b relative to each other.

Further, since the elastic contact member 7c has only a short effectivelength, the elastic contact member 7c needs to be reduced in thicknessin order to ensure a specified spring constant. Therefore, the elasticcontact member 7c tends to deform during the process of caulking orother fixing work, which leads to a problem of troublesome assemblywork.

In the light of the aforementioned third technical problem, a thirdobject of the present invention is to provide an electromagnetic relaywhich will not vary in performance characteristics even with varyingoutside temperature, and which is easy to assemble.

DISCLOSURE OF THE INVENTION

To achieve the first object, in a first characteristic aspect of thepresent invention, there is provided an electromagnetic relay in which acontact mechanism mounted on a base is driven by a card which movesreciprocatingly in parallel to an axis of an electromagnet block mountedon the base as the electromagnet block is energized and de-energized,wherein the base comprises a guide portion for restricting the card inits position.

Therefore, according to the first aspect of the present invention, thecard reciprocatingly moves while it is restricted in position by theguide portion provided in the base. This eliminates the need ofassembling the card to the elastic contact member, which process wouldbe involved in the prior art. Therefore, the elastic contact member willnever undergo plastic deformation so that there will occur no variationsin the performance characteristics.

Also, since a single operation of assembling the card to the guideportion provided in the base is sufficient, the number of assemblingoperations is reduced so that the work becomes less troublesome thanwould be when the card is assembled to the elastic contact member of themovable contact terminal. Thus, the productivity is improved.

Further, the card is simply brought into contact with the elasticcontact member of the movable contact terminal, free from such skewcontact as would occur in the prior art. Thus, the contact less wears sothat its service life is prolonged advantageously.

A second characteristic aspect of the present invention is that theguide portion is provided on one side of the base within a range fromits central portion toward the contact mechanism. According to thesecond aspect, since the guide portion is located near the contactmechanism, the card is reduced in deflection so that the performancecharacteristics are improved.

A third characteristic aspect of the present invention is that the guideportion is provided in a pair in line with each other in the base.According to the third aspect, the card is supported at two points sothat the assembly precision is further improved and therefore theperformance characteristics are improved.

A fourth characteristic aspect of the present invention is that theguide portion has an insertion hole for restricting the card in itsposition. According to the fourth aspect, since a single operation ofinserting the card into the insertion hole of the guide portion issufficient, the assembling work becomes easy and the productivity isimproved.

A fifth characteristic aspect of the present invention is that a pair ofguide projections are projectingly provided in the base, while a guideprojecting portion for restricting up and down rattling of the card isformed at a ceiling surface of the casing fittable to the base.According to the fifth aspect, since the guide portion to be provided inthe base is not necessarily required to be of a generally U-shaped archtype, the base is easy to mold and the mold is simple to manufacture.

A sixth characteristic aspect of the present invention is that the guideportion provided in the base comprises a pair of elastic claws to whichthe card can be snap fitted at a press in the thickness direction.According to the sixth aspect, since the card can be assembled to thebase with one-touch operation, the productivity is improvedadvantageously.

To achieve the second object, in a seventh characteristic aspect of thepresent invention, there is provided an electromagnetic relay whichcomprises a base having an insulating wall of a generally U-shape in itsplan view molded integrally at a generally center of a top surface ofthe base; an electromagnet block which is formed by winding a coilaround an iron core and which is located at the top surface of the baseso as to be surrounded by the insulating wall on one end side thereof; acontact mechanism located on one side of the top surface of the basepartitioned by the insulating wall from one end side of theelectromagnet block; an insulating cover covering an upper opening ofthe insulating wall; and a card for driving the contact mechanism byreciprocatingly moving axially above the insulating cover as theelectromagnet block is energized and de-energized.

According to the seventh aspect of the present invention, theelectromagnet block can be assembled from above to the top surface ofthe base partitioned by the insulating wall. Therefore, theelectromagnet block can be positioned relative to the contact mechanismwith higher assembly precision than in the prior art, so that novariations will occur in the move extent of the card. Thus, theperformance characteristics can be prevented from variations.

Also, since there is no need of molding the cylindrical frame integrallywith the base, as in the prior art, the base configuration becomessimpler than the prior art counterpart, so that the molding of the baseas well as the manufacture of the mold are facilitated.

Further, since the electromagnet block, like the other components, canbe assembled to the base from above, the automatic assembling machinesare simpler to arrange. Thus, the automatization of the assembly line isfacilitated.

An eighth characteristic aspect of the present invention is that theinsulating cover has a generally "L"-shaped cross section, and covers atits vertical portion at least a central outer side face of theinsulating wall so as to partition the electromagnet block and thecontact mechanism from each other in a double structure. According tothe eighth aspect of the present invention, since the electromagnetblock and the contact mechanism are partitioned in a double structure,the creepage distance between them is prolonged so that the insulatingcharacteristic is further improved.

A ninth characteristic aspect of the present invention is that a pair ofprojecting portions for sandwiching end portion side faces of the corethat are exposed from the electromagnet block are provided at a bottomsurface of the insulating cover. According to the ninth aspect of thepresent invention, since a pair of projecting portions provided in theinsulating cover sandwich the end portion side faces of the core torestrict the position of the electromagnet block, the electromagnetblock can be prevented from rattling in the widthwise direction so thatthe assembly precision is improved.

A tenth characteristic aspect of the present invention is that at leastone projecting portion for ensuring the reciprocating movement of thecard is provided in the top surface of the insulating cover so as to bein contact with the ceiling surface of the casing. According to thetenth aspect, the projecting portion provided at the top surface of theinsulating cover contacts and supports the ceiling surface of thecasing. Therefore, even if the casing is loaded with external force, theprojecting portion receives this external force, preventing the ceilingsurface of the casing from making contact with the card. Thus, thereciprocating movement of the card is ensured.

An eleventh characteristic aspect of the present invention is that theelectromagnet block is positioned by pressing it to the base with theinsulating cover having at its top surface a projecting portion whichcomes into press contact with the ceiling surface of the casing fittedto the base. According to the eleventh aspect, the electromagnet blockis positioned by pressing it with the insulating cover having at its topsurface the projecting portion that comes in press contact with theceiling surface of the casing fitted to the base. Therefore, theelectromagnet block is restricted in position in the vertical direction,so that the electromagnet block is prevented from rattling in thevertical direction. Thus, high precision assembly can be attained.

A twelfth characteristic aspect of the present invention is that atleast one guide projection for guiding the reciprocating movement of thecard is provided at the top surface of the insulating cover. Accordingto the twelfth aspect, the card is restricted in position by makingcontact with the guide projection provided at the top surface of theinsulating cover. Thus, the performance characteristics are free fromvariations, so that the card will never fall out from the insulatingcover.

A thirteenth characteristic aspect of the present invention is that aprojecting portion for restricting the card in its position by makingcontact with the card that has returned to its original position isprovided at the top surface of the insulating cover. According to thethirteenth aspect, the card is stopped at a specified position when itreturns. There the card keeps a stable extent of movement so that themovable contact is prevented from varying in the move extent. As aresult, uniform performance characteristics are obtained,advantageously.

To achieve the third object, according to a fourteenth characteristicaspect of the present invention, there is provided an electromagneticrelay comprising a contact mechanism composed of a fixed contactterminal erectly provided on a base, and a movable contact terminalformed of an elastic contact member which has a movable contact thatcontacts and separates from a fixed contact of the fixed contactterminal, and which is erectly provided on the base, the movable contactbeing made to contact and separate from the fixed contact by rocking theelastic contact member in its thickness direction, wherein the fixedcontact is located above a top surface of the base, while, out of theelastic contact member of the movable contact terminal formed byarranging a generally U-shaped electrically conductive thin plate springmaterial into an arch configuration, at least an upper end edge portionof an elastic upper side portion continuous to an elastic base portionsupported by the base is bent horizontally, and wherein the movablecontact is provided at a lower end portion of an elastic verticalportion continuous to the elastic upper side portion.

According to the fourteenth aspect, the movable contact and the fixedcontact can be located near the top surface of the base. Therefore, evenif the movable contact terminal and the fixed contact terminal areinclined due to thermal deformation of the base, the fixed contact andthe movable contact are less deflected, so that variations in theperformance characteristics due to shifts of the fixed contact and themovable contact relative to each other can be prevented.

Also, since the elastic contact member has a longer effective lengththan the prior art counterpart, the. exposed area is increased so that amovable contact terminal good at heat radiation can be obtained.

Further, since the elastic contact member has a long effective length sothat a desired spring constant can be easily obtained, the elasticcontact member can be increased in thickness. Therefore, the elasticcontact member is prevented from deformation during the process ofcaulking or other work, whereby the workability is improved.

In particular, since at least the upper end edge portion of the elasticupper side portion is bent horizontally, the elastic upper side portionis formed into a generally "L"-shape in cross section. Therefore, theelastic upper side portion has large rigidity, so that the elasticvertical portion is less distorted. Thus, the elastic vertical portioncan be rocked at accurate angles in the thickness direction.

Furthermore, there can be provided an electromagnetic relay in which theelastic vertical portion is free from any complex stress and thecontacts can be opened and closed by driving the elastic contact memberwith a relatively small pressing force.

A fifteenth characteristic aspect of the present invention is that thewhole elastic upper side portion of the elastic contact member is benthorizontally. According to the fifteenth aspect, the elastic upper sideportion will never be formed into a generally "L"-shape in crosssection, so that the elastic vertical portion can be rocked on its baseportion. Therefore, even with height restrictions, the elastic verticalportion is long in the effective length and easy to deform. As a result,there can be provided an electromagnetic relay in which the contacts canbe opened and closed by driving the elastic contact member with arelatively small pressing force, advantageously.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of an electromagnetic relayaccording to a first embodiment;

FIG. 2 is a sectional view of the electromagnetic relay according to thefirst embodiment;

FIG. 3 is a sectional view of a main part of FIG. 2;

FIG. 4 is a side view of a main part of another application exampleaccording to the first embodiment;

FIGS. 5A through 5C illustrate a contact mechanism of anotherapplication example according to the first embodiment, where FIGS. 5A,5B, and 5C are main-part enlarged views showing the state prior tooperation, during operation, and after operation of the contactmechanism, respectively;

FIG. 6 is an exploded perspective view of an electromagnetic relayaccording to a second embodiment;

FIG. 7 is a main-part sectional view of the electromagnetic relayaccording to the second embodiment;

FIG. 8 is an exploded perspective view of an electromagnetic relayaccording to a third embodiment;

FIG. 9 is an exploded perspective view of an electromagnetic relayaccording to a fourth embodiment;

FIG. 10 is an exploded perspective view showing a fifth embodiment ofthe electromagnetic relay according to the present invention;

FIG. 11 is a perspective view representing a casing of theelectromagnetic relay shown in FIG. 10;

FIG. 12 is a planar sectional view of the electromagnetic relay shown inFIG. 10;

FIG. 13 is a front sectional view of the electromagnetic relay shown inFIG. 10;

FIG. 14 is a partly rear sectional view of the electromagnetic relayshown in FIG. 10;

FIG. 15 is a plan view showing a hoop material stamped into a coreaccording to the fifth embodiment of the present invention;

FIG. 16 is a plan view showing the hoop material of FIG. 15 with thecore bent;

FIG. 17 is a sectional view taken along the line XVII--XVII of FIG. 16;

FIGS. 18A through 18D illustrate a fixed contact terminal according tothe fifth embodiment of the present invention, where FIGS. 18A, 18B,18C, and 18D are a plan view, a left side view, a front view, and aright side view, respectively;

FIGS. 19A through 19D illustrate a modification of the fixed contactterminal according to the present invention, where FIGS. 19A, 19B, 19C,and 19D are a plan view, a left side view, a front view, and a rightside view, respectively;

FIG. 20 is an exploded perspective view for explaining the way how theinsulating cover is assembled, according to the present invention;

FIG. 21 is an exploded perspective view showing a sixth embodiment ofthe electromagnetic relay according to the present invention;

FIG. 22 is an exploded perspective view showing a seventh embodiment ofthe electromagnetic relay according to the present invention;

FIG. 23 is an exploded perspective view showing an eighth embodiment ofthe electromagnetic relay according to the present invention;

FIG. 24 is an exploded perspective view showing a ninth embodiment ofthe electromagnetic relay according to the present invention;

FIG. 25 is an exploded perspective view of an electromagnetic relayaccording to the prior art; and

FIG. 26 is a sectional view of the electromagnetic relay according tothe prior art.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments according to the present invention will now be describedwith reference to the accompanying drawings of FIGS. 1 through 24.

The electromagnetic relay according to the first embodiment, as shown inFIGS. 1 to 3, generally comprises a base 10, an electromagnet block 20to which a moving core 30 is assembled via a hinge spring 40, a contactmechanism 50, a slide type card 60, and a casing 70.

The base 10 has a frame 11 of a generally U-shape in cross sectionintegrally molded at a central portion of its top surface, so as to forma cavity 12. A deeper opening of the cavity 12 is sealed by aninsulating wall 13 of the frame 11 as shown in FIG. 2. The base 10 alsohas press-fit grooves 14, 15, 16 for assembling a later-describedmovable contact member 53 or the like sideways to places outward of theinsulating wall 13 to thereby form the contact mechanism 50, in such away that the press-fit grooves 14, 15, 16 are alternately staggered.Further, at an edge portion near the contact mechanism 50, out of thetop surface of the frame 11, a generally U-shaped guide portion 17 forguiding a later-described card 60 is projectingly provided.

The electromagnet block 20 is formed by winding a coil 24 around abarrel of a spool 23 (not shown) having flanges 21, 22 at both ends,inserting a core 25 of a generally T-shape in cross section into athrough hole (not shown) provided in the barrel, and taking one endportion exposed in the front face of the flange 21 as a magnetic-poleportion 25a while fixedly caulking the other end portion projected fromthe flange 22 to a vertical portion of a yoke 26 bent in a generallyL-shape in cross section.

The yoke 26 has positioning projecting portions 26b, 26b projected fromboth-side upper corners of its horizontal-portion end face 26a, and thepositioning projecting portions 26b, 26b are projected from the frontface of the flange 21.

The flange 21 of the spool 23 has, at both-side edge portions of itsfront face, slits 21a, 21a for engaging a later-described hinge spring40. Further, the flange 21 of the spool 23 has coil terminals 27, 27press-fitted and fixed sideways into its opposite side end faces, andleads are bound up and soldered to binder portions 27a located at upperends of the coil terminals 27.

The moving core 30 has such a front shape that it can be assembled to acentral portion of the front face of the flange 21. Positioning-usecutouts 31, 31 engageable with the positioning projecting portions 26b,26b of the yoke 26 are provided at both-side edge portions near thelower end of the moving core 30, while cutouts 32 engageable with thelater-described card 60 are provided at both-side edge portions near theupper end of the moving core 30.

When the cutouts 31, 31 of the moving core 30 are engaged with thepositioning projecting portions 26b, 26b of the yoke 26, respectively,the moving core 30 is opposed to the magnetic-pole portion 25a of thecore 25 so that it can contact and separate from the magnetic-poleportion 25a.

The hinge spring 40 is formed of a thin plate spring material having agenerally E-shape in its front view. When arms 41, 42 on both sides ofthe hinge spring 40 are press-fitted and fixed into the slits 21a, 21aof the spool 23, a long tongue 43 extending from a central portion ofthe hinge spring 40 presses a rear-face lower end portion of the movingcore 30 so that the moving core 30 is hinged so as to be rockable on thehorizontal-portion end face 26a of the yoke 26 as a fulcrum.

Then, the electromagnet block 20 to which the moving core 30 isassembled via the hinge spring 40 is inserted into the cavity 12 of thebase 10 sideways, whereby they are integrally assembled.

According to the present embodiment, the hinge spring 40 is locatedbelow the rear face of the moving core 30, whereby the dead spacegenerated on the rear side of the moving core 30 can be effectivelyutilized. This advantageously allows the downsizing of the relay unit.

The contact mechanism 50 comprises a pair of fixed contact terminals 51,52 and a movable contact terminal 53. Fixed contacts 51a, 52a of thefixed contact terminals 51, 52 and a movable contact 53a of the movablecontact terminal 53 are located at positions decentered from widthwisecenter lines of the individual contact terminals by specified distances,respectively. Thus, the contacts 51a, 52a, 53a are subject to not onlybending moment but also torsional moment, so that they are good atanti-deposition characteristic.

Still, since the contacts are located at positions decentered from thewidthwise center lines in the individual base portions where the fixedcontact terminals 51, 52 and the movable contact terminal 53 areattached, the contact terminals have substantially longer effectivespring lengths than when the contacts are located on the center lines.Thus, the electromagnetic relay advantageously can be reduced in heightto its corresponding extent.

In addition, the fixed contact terminals 51, 52 and the movable contactterminal 53 are not limited to straight types, but may instead be thosehaving bent shapes in view of material handling.

Terminal portions 51b, 52b of the fixed contact terminals 51, 52 and aterminal portion 53b of the movable contact terminal 53 are press-fittedsideways into the press-fit grooves 14, 15, 16 provided in the base 10(FIG. 2), respectively, whereby the fixed contacts 51a, 52a are opposedto each other with the movable contact 53a interposed therebetween.

According to the present embodiment, since the fixed contact terminals51, 52 and the movable contact terminal 53 are press-fitted sideways andthereby fixed to the press-fit grooves 14, 15, 16 of the base 10,creepage distances between the terminal portions are longer than thoseof the prior art. Moreover, arch type terminal portions as would beinvolved in the prior art are not necessitated, and the contact memberscan be increased in width. Thus, even if a large current is passedtherethrough, the contact members are kept low in heat-generatingtemperature and large in spring force, advantageously.

The slide type card 60, as shown in FIGS. 1 and 2, is formed of asynthetic resin plate material with a generally rectangular shape in itsplan view, and has a rectangular fitting hole 61 at its central portion.The slide type card 60 has a drive-use projecting portion 62projectingly provided at a center of one end face, a pair of elasticengagement legs 64, 64 projected on both sides of the drive-useprojecting portion 62, and a long tongue 63 projected from a center ofthe other end face coaxially with the drive-use projecting portion 62.

Then, the long tongue 63 of the slide type card 60 is inserted into aninsertion hole 17a of the guide portion 17 of the base 10, while themoving core 30 is positioned between the pair of elastic engagement legs64, 64 and, as such, pushed in to be engaged therewith. Thus, the card60 is supported so as to be slidable.

The casing 70 has such a box shape as to be fittable to the base 10, andhas an annular projecting portion 71 projected inward from a centerportion of its ceiling surface. Further, the casing 70 has a gas bleederhole 72 at an edge portion of its top surface and a projection 73 thatmay be bent off to form a gas bleeder hole for bleeding out nitric acidgas and the like generated during use.

When the casing 70 is fitted to the base 10, to which internalcomponents such as the electromagnet block 20 have been assembled, thelower end portion of the projecting portion 71 makes contact with thetop surface of the frame 11 of the base 10 via the fitting hole 61 ofthe card 60 (FIG. 2). Then, a sealing agent (not shown) is injected tothe bottom surface of the base 10 and solidified so as to seal it. Afterinside gas is bled through the gas bleeder hole 72, the gas bleeder hole72 is thermally fused and thereby sealed. Thus, the assembly work iscompleted.

According to the present embodiment, since the ceiling surface of thecasing 70 is restricted in position via the projecting portion 71, theceiling surface of the casing 70 will not deflect even if external forceis applied to the top surface of the casing 70. Thus, the card 60 is nothindered from operating.

Also, if the gate of the mold is located coaxially with the projectingportion 71, the flow of molding resin is facilitated, whereby themoldability is improved advantageously.

In addition, the projecting portion 71 provided in the casing 70 is notlimited to one which is brought into contact with the top surface of theframe 11 provided in the base 10. Alternatively, for example, theprojecting portion 71 may be brought into contact with the spool 23 ofthe electromagnet block 20. Otherwise, the projecting portion 71 may beprovided at the top surface of the frame 11 and brought into contactwith the ceiling surface of the casing 70. Further, the card 60 may havenot a fitting hole but a cutout provided therein.

Next described is the operation of the electromagnetic relay having theabove-described construction.

With the electromagnet block 20 unexcited, the movable contact terminal53 is biased leftward in FIG. 2 by its own spring force, with themovable contact 53a in contact with the fixed contact 51a.

When the electromagnet block 20 is excited with a voltage applied to thecoil 24, the magnetic-pole portion 25a of the core 25 attracts themoving core 30, causing the moving core 30 to rock. Thereby, the upperend portion of the moving core 30 presses the end face of the projectingportion 62 provided in the card 60. Therefore, the slide type card 60,which is guided by the guide portion 17, is slid rightward in FIG. 2, sothat the long tongue 63 of the card 60 presses the upper end portion ofthe movable contact terminal 53. As a result, the movable contactterminal 53 rocks, whereby the movable contact 53a is switched from thefixed contact 51a to the fixed contact 52a.

When the electromagnet block 20 is demagnetized, the movable contactterminal 53 returns to the original position by its own spring force,whereby the slide type card 60 is pressed back so that the moving core30 rocks in a direction opposite to the foregoing. Thus, the movablecontact 53a is switched from the fixed contact 52a to the fixed contact51a, returning to the original state.

The above first embodiment has been described on a case where the fixedcontacts 51a and 52a are opposed to each other with the movable contact53a interposed therebetween. However, the present invention is notnecessarily limited to this, but may also be applied to anelectromagnetic relay, for example, in which the movable contact 53a isput into and out of contact with only the fixed contact 52a, as shown inFIG. 4.

Also, the card 60 may be so arranged not merely that the movable contact53a is pressed against the fixed contact 52a, but that, for example asshown in FIGS. 5A to 5C, a rounded surface 63a is formed at an endportion of the long tongue 63 of the card 60.

According to this application example, when the upper end portion of themovable contact terminal 53 is pressed by the long tongue 63 of the card60 in FIG. 5A, the press point is decentered from the center of themovable contact 53a. Therefore, the surface of the movable contact 53ais shifted by the press of the long tongue 63 in such a way as to rubagainst the surface of the fixed contact 52a (FIGS. 5B and 5C), wherebythe contacts can be effectively prevented from deposition, to anadvantage.

A second embodiment, as shown in FIG. 6, has an arrangement that,whereas the card 60 is restricted in position by the arch type guideportion 17 of a generally U-shape provided in the base 10 in theabove-described first embodiment, an insertion hole 18a is defined by apair of guide projections 18, 18 provided in the base 10 and a guideprojection portion 74 provided at the ceiling surface of the casing 70(see FIG. 7), whereby the card 60 is restricted in position.

According to the present embodiment, the molding to the base 10 becomeseasier than in the first embodiment, facilitating the manufacture of themold, advantageously. The rest of the arrangement is similar to that ofthe above first embodiment and therefore omitted in description.

A third embodiment, as shown in FIG. 8, has an arrangement that, whereasthe card 60 is restricted in position by inserting the long tongue 63 ofthe card 60 into the insertion hole 17a of the generally U-shaped archtype guide portion 17 provided in the base 10 in the above-describedfirst embodiment, the long tongue 63 of the card 60 is pressed fromabove to between a pair of elastic claws 19, 19 provided in the base 10,so that the card can be mounted with one-touch operation.

According to the present embodiment, since the card 60 can be assembledto the base 10 from above with one-touch operation, the productivity isimproved advantageously. The rest of the arrangement is similar to thatof the above-described first embodiment and therefore omitted indescription.

A fourth embodiment, as shown in FIG. 9, has an arrangement that,whereas the card 60 is restricted in position by one guide portion inany of the above-described embodiments, the card 60 is restricted inposition by a pair of generally U-shaped arch type guide portions 17, 17projectingly provided in line with each other. Reference numeral 65denotes an engagement projection of the card 60. The guide portions 17,17 according to the present embodiment are not limited to theaforementioned shape, but, for example, the shapes of the guide portionsof the second and third embodiments are also applicable as a matter ofcourse. The rest of the arrangement is similar to that of the firstembodiment and therefore omitted in description.

According to the present embodiment, the card 60 having a cross shape isassembled by inserting the long tongue 63 into the insertion holes 17a,17a of the guide portions 17, 17, in which case the card 60 isrestricted in position at two points. Thus, the card is further reducedin deflection, so that the performance characteristics are improvedadvantageously.

An electromagnetic relay according to a fifth embodiment, as shown inFIGS. 10 through 20, generally comprises a base 110, an electromagnetblock 120 to which a moving core 140 is assembled via a hinge spring145, a contact mechanism 150, an insulating cover 160, a card 170, and acasing 180.

The base 110 has a fitting recess 112 defined by integrally molding aninsulating wall 111 of a generally U-shape in its plan view in a centralportion of its top surface. An engagement groove 113 which communicateswith the fitting recess 112 and which can slidingly engage alater-described core 130 of the electromagnet block 120 is provided inthe vertical direction at a central portion of the inner surface of theinsulating wall 111. Also, in the base 110, terminal holes 114, 115 intowhich later-described fixed contact terminals 151, 152 can bepress-fitted from above are provided at positions located outward of theengagement groove 113 out of the top surface of the base 110, andbesides a terminal hole (not shown) which is adjacent to these terminalholes via a partition wall 116 and into which a movable contact terminal153 can be press-fitted from above is provided. Further, in the base110, a projecting portion 117 which serves as a transfer guide and whichcan locate the later-described electromagnet block 120 into position isprovided at a top surface end portion opposite to the terminal holes114, 115, out of the top surface of the base 110. In addition, referencenumerals 118, 118 denote terminal holes of a coil terminal 128.

The electromagnet block 120 is formed by winding a coil 125 around abarrel 124 of a spool 123 having flanges 121, 122 at both ends (see FIG.13), and inserting a single arm 131 of the core 130 bent into agenerally U-shape in cross section, into a center hole 124a provided inthe barrel 124, where a projecting end portion of the single arm 131 isassigned as a magnetic-pole portion 131a while an end portion of theremaining single arm 132 is assigned as a magnetic-pole portion 132a.

The spool 123 is so constructed that an anti-dropout projecting portion126 is provided at a lower side edge portion of its flange 121 so as tobe projected sideward, while the coil terminal 128 is press-fitted andthereby fixed into a terminal hole 127a of a base seat 127 provided at alower side edge portion of the flange 122 of the spool 123 (whereanother deeper terminal hole is not shown). At the upper end portion ofthe coil terminal 128, leads of the coil 125 are bound up and soldered.

It is noted that the anti-dropout projecting portion 126 is designed toprevent the flange 121 of the spool 123 from dropping and hanging at anyjoint of the belt conveyor while the electromagnet block 120 is conveyedby the belt conveyor in the assembly line, thereby preventing the spool123 from damage and the coil 125 from disconnection.

The core 130, as shown in FIGS. 15 to 17, is formed by stamping a hoopmaterial 190 of a thick strip-shaped material, bending it into agenerally U-shape in cross section, and then cutting it off, where apair of ribs 134, 134 for use of positioning are projected from bothside faces of the bending portion 133. It is noted that one single arm132 out of the single arms 131, 132 of the core 130 is large in width atits tip so as to be small in magnetic reluctance. Also, a shallow recess131b for engaging with a later-described hinge spring 145 is provided inproximity to the magnetic-pole portion 131a of the single arm 131.

The moving core 140 is formed by stamping a plate-shaped magneticmaterial, where a taper surface 141 is formed by bending a lower endportion of the magnetic material toward the inner surface side. Aportion of the core 130 that is attracted to the wide magnetic-poleportion 132a is assigned as a wide portion 142, where a pair of cutouts143, 143 are provided at both-side end faces upward of the wide portion142.

The hinge spring 145, as shown in FIG. 13, is made of a thin-platespring material bent into a generally "L"-shape in cross section, whereits vertical portion 146 is fixed to the rear surface of the moving core140.

Then, a horizontal portion 147 of the hinge spring 145 is press-fittedinto a gap between the inner circumferential surface of the center hole124a provided in the spool 123 and the lower surface of the single arm131 of the core 130, while an elastic claw 148 formed by louvering thehorizontal portion 147 of the hinge spring 145 is engaged with theshallow recess 131b provided at the lower surface of the single arm 131so that the elastic claw 148 is prevented from falling out. Thereby, themoving core 140 is supported rockable.

According to the present embodiment, the taper surface 141 of the movingcore 140 is normally held in linear contact with the lower edge portionof the end face of the magnetic-pole portion 131a. Therefore, even whenthe moving core 140 rocks, the rocking fulcrum will not move so thatstable performance characteristics are obtained. As a result, it is nolonger necessary to form a difficult-to-machine taper surface at the endface of the magnetic-pole portion 131a of the core 130. Thus, the core130 becomes easy to manufacture, advantageously.

Subsequently, the electromagnet block 120, to which the moving core 140is assembled via the hinge spring 145, is fitted from above to thefitting recess 112 of the base 110, while at the same time theprojecting portion 126 of the spool 123 and the ribs 134, 134 of thecore 130 are fitted to the engagement groove 113 one by one, whereby theelectromagnet block 120 is assembled.

According to the present embodiment, the ribs 134, 134 provided at thebending portion 133 of the core 130 are slid and engaged from above withthe engagement groove 113 of the spool 123, whereby the electromagnetblock 120 can be assembled to the base 110 with high precision,advantageously.

The contact mechanism 150 comprises a pair of fixed contact terminals151, 152, and a movable contact terminal 153. Fixed contacts 151a, 152aof the fixed contact terminals 151, 152 are provided at lower positionsin proximity to terminal portions 151b, 152b, respectively.

Meanwhile, the movable contact terminal 153, as shown in FIGS. 18A to18D, is formed by caulking and fixing a generally arch type elasticcontact member 154 separately at the top end of its terminal portion153b. This elastic contact member 154 comprises an elastic base portion154a, an elastic upper side portion 154b, and an elastic verticalportion 154c. The elastic upper side portion 154b is bent horizontallyon the whole, while the elastic vertical portion 154c has a movablecontact 153a provided thereon and a through hole 153c formed therein.

According to the present embodiment, since the elastic vertical portion154c is rockable on its base portion, the elastic vertical portion 154chas a long effective length and will easily deform even when its heightis limited. Thus, there can be provided an electromagnetic relay inwhich the contacts can be opened and closed by driving the elasticvertical portion 154c with a relatively small pressing force.

Also, since the elastic contact member 154 is long in its overalleffective length, there can be obtained a movable contact terminal 153which is large in exposed area and superior in heat radiation.

Further, since the elastic contact member 154 is long in its overalleffective length so that a desired spring constant can be easilyattained, the elastic contact member 154 can be increased in thickness.Therefore, the elastic contact member 154 is prevented from deformingduring the caulking or other process, offering an advantage of higherworkability.

In addition, the movable contact terminal 153 is not limited to theaforementioned one. Alternatively, for example as shown in FIGS. 19A to19D, it may be such that the elastic upper side portion 154b of theelastic contact member 154 is bent horizontally at only a fore edgeportion thereof to form a vertical portion 154d, whereby the elasticupper side portion 154b is formed into a generally "L"-shape.

According to this arrangement, since the elastic upper side portion 154bis large in rigidity, the elastic vertical portion 154c is unlikely todistort. Thus, the elastic vertical portion 154c can be rocked atcorrect angles.

Also, the elastic vertical portion 154c undergoes no complex stress, sothat the contacts can be opened and closed by driving the elasticcontact member 154 with a relatively small pressing force,advantageously. The rest of the arrangement is similar to that of theabove-described movable contact terminal 153 and therefore omitted indescription.

Then, the terminal portions 151b, 152b of the fixed contact terminals151, 152 and the terminal portion 153b of the movable contact terminal153 are press-fitted into the terminal holes 114, 115 provided in thebase 110 (where the terminal hole of the movable contact terminal 153 isnot shown), whereby the movable contact 153a is positioned between thefixed contacts 151a and 152a opposite to each other at a specifiedinterval so that the movable contact 153a can be brought into and out ofcontact therewith.

According to the present embodiment, since the fixed contacts 151a, 152aand the movable contact 153a are disposed in proximity to theircorresponding terminal portions 151b, 152b, and 153b, respectively, eachat a low position, the fixed contacts 151a, 152a and the movable contact153a are positioned in proximity to the top surface of the base 110.Therefore, for example, even if the fixed contact terminals 151, 152 andthe movable contact terminal 153 are inclined due to thermal deformationof the base 110, the fixed contacts 151a, 152a and the movable contact153a are less deflected, whereby variations in the. performancecharacteristics due to shifts among the fixed contacts 151a, 152a andthe movable contact 153a can be prevented advantageously.

The insulating cover 160 is a resin molded product having a generally"L"-shaped cross section and designed to insulate the contact mechanism150 from the electromagnet block 120. In the insulating cover 160, aprojecting portion 161 for restricting the return position of alater-described card 170 and a projecting portion 162 for ensuring thereciprocating movement of the card 170 are provided at top surfacecentral portions of a horizontal portion 160a of the insulating cover160, while a guide projection 163 for guiding the card 170 andpreventing it from falling off is provided at a top surface corner ofthe horizontal portion 160a. Further, as shown in FIG. 20, in theinsulating cover 160, a pair of projecting portions 164, 164 forsandwiching the bending portion 133 of the core 130 and a projection 165which will come into press contact with the upper surface of the singlearm 132 of the core 130 are provided at the lower surface of thehorizontal portion 160a of the insulating cover 160.

When the insulating cover 160 is fitted and fixed to the insulating wall111 of the base 110, to which the electromagnet block 120 has beenassembled, the projecting portions 164, 164 of the insulating cover 160sandwich the bending portion 133 of the core 130, and moreover push downits ribs 134, 134 for positional restriction, while the projection 165of the insulating cover 160 is brought into contact with the uppersurface of the single arm 132 of the core 130, thereby preventing theelectromagnet block 120 from falling off.

According to the present embodiment, a vertical portion 160b of theinsulating cover 160 overlaps with the insulating wall 111 of the base110 into a double-wall structure. Thus, the creepage distance betweenthe electromagnet block 120 and the contact mechanism 150 is prolonged,so that the insulating characteristic is further improvedadvantageously.

The slide type card 170 is a synthetic resin molded product having agenerally rectangular shape in its plan view and has a rectangularfitting hole 171 at a central portion thereof. The slide type card 170has a long tongue 172 extending downward from a central portion of oneend face, and a fitting projection 173 and a press projection 174provided downward of the long tongue 172. Meanwhile, the slide type card170 has a drive-use projecting portion 175 projectingly provided at acentral portion of the other end face, and a pair of elastic engagementlegs 176, 176 provided so as to be projected from both sides of thedrive-use projecting portion 175.

Further, in the card 170, a linear projection 177 in association with aguide rail is provided at the lower surface of the card 170 along thewidthwise direction. The linear projection 177 is designed to preventthe card 170 from falling off when the card 170 is slid along the guiderail (not shown), and thereby to align the card 170 in one direction.However, the linear projection 177 is not limited to this arrangementbut may also be provided at the upper surface of the card 170.Otherwise, two projections may be provided in line to substitutetherefor.

According to the present embodiment, out of the long tongue 172 and thelinear projection 177, at least either one of them is engaged with theedge portion of the guide rail so that the card 170 is automaticallyaligned in one direction. Thus, the assembly work, particularly theautomatization of assembly is further facilitated, advantageously.

Then, the fitting projection 173 of the slide type card 170 is insertedinto the through hole 153c of the movable contact terminal 153 while themoving core 140 is positioned between the pair of elastic engagementlegs 176, 176 and pushed in to be engaged with the cutouts 143, 143.Thereby, the card 170 is supported so as to be reciprocatingly movable.

According to the present embodiment, the long tongue 172 is extendeddownward from an end face central portion of the card 170, and thefitting projection 173 and the press projection 174 are provideddownward of the long tongue 172. Thus, even if any vibration or impactforce is applied from external, the long tongue 172 absorbs and relaxesit. Therefore, since the long tongue 172 functions to prevent anymalfunction due to vibrations or the like, high reliability is attained.

Also, since the contact mechanism 150 is limited in structure, thedegree of freedom for design is large to an advantage.

The casing 180, as shown in FIG. 11, has such a box shape as to befittable to the base 110. In the casing 180, a gas bleeder hole 181 isprovided at one-side edge portion of its ceiling surface, while aprojection 182 is further provided which allows a gas bleeder hole to beformed by folding and removing it for the purpose of bleeding out nitricacid gas generated during use.

When the casing 180 is fitted to the base 110, to which the internalcomponents such as the electromagnet block 120 have been assembled, asshown in FIG. 13, the ceiling lower surface of the casing 180 is broughtinto press contact with the projecting portion 162 of the insulatingcover 160, so that the projection 165 of the insulating cover 160presses the single arm 132 of the core 130, thereby restricting theposition of the electromagnet block 120. Then, a sealing agent 183 isinjected to the bottom surface of the base 110, and solidified to sealit. After inside gas is purged through the gas bleeder hole 181, the gasbleeder hole 181 is thermally fused so as to be sealed. Thus, theassembly work is completed.

According to the present embodiment, since the casing 180 presses thecore 130 via the projecting portion 162 and projection 165 of theinsulating cover 160, the core 130 can be prevented from coming out.Moreover, even if any external force is loaded to the ceiling surface ofthe casing 180, the projecting portion 162 and projection 165 of theinsulating cover 160 receive the force. Thus, the ceiling surface of thecasing 180 is hardly distorted so that the card 170 is not hindered fromreciprocating movement, advantageously.

Now the operation of the electromagnetic relay having theabove-described construction is described.

If the electromagnet block 120 is unexcited as shown in FIG. 13, thecard 170 is urged toward the moving core 140 by the spring force of theelastic contact member 154 of the movable contact terminal 153. Thus,the inner surface of its fitting hole 171 is put into contact with theprojecting portion 161 of the insulating cover, whereby the card 170 isrestricted in position, while the movable contact 153a is put intocontact with the fixed contact 151a.

When the electromagnet block 120 is excited with a voltage applied toits coil 125, the magnetic-pole portion 132a of the core 130 attractsthe moving core 140, whereby the moving core 140 rocks on the fulcrum ofan endface lower edge portion of the magnetic-pole portion 131a of thecore 130, such that its wide portion 142 is attracted to themagnetic-pole portion 132a of the single arm 132. As a result, themoving core 140 presses the drive-use projecting portion 175 of the card170 so that the card 170 slidingly moves toward the contact mechanism150 against the spring force of the elastic contact member 154. Thus,the press projection 174 provided in the long tongue 172 of the card 170presses the elastic vertical portion 154c of the movable contactterminal 153, whereby the movable contact 153a is switched from thefixed contact 151a to the fixed contact 152a.

Subsequently, when the electromagnet block 120 is demagnetized, the card170 is pushed back by the spring force of the elastic contact member154, causing the wide portion 142 of the moving core 140 to be separatedfrom the magnetic-pole portion 132a of the core 130. As a result, theinner surface of the fitting hole 171 of the card 170 comes into contactwith the projecting portion 161 of the insulating cover 160, whereby thecard 170 is restored to the original position, while the movable contact153a is switched to the fixed contact 151a so as to be restored to theoriginal state.

According to the present embodiment, since the card 170 is restricted inposition by one projecting portion 161 and four guide projections 163provided in the insulating cover 160, the performance characteristicswill not vary, nor will the insulating cover 160 fall out.

According to the present embodiment, since the taper surface 141 isformed in the moving core 140 to prevent the rocking fulcrum frommoving, there is no need of forming a taper surface at an end face ofthe magnetic-pole portion 131a that is difficult to machine. Thus, themanufacture of the core 130 is facilitated, advantageously.

In addition, in order to prevent the card 170 from falling off, it isunnecessary to provide all of the aforementioned projecting portion 161and four projections 163, but it is allowed to provide only theprojecting portion 161 or to provide the projecting portion 161 and twoprojections 163.

It may also be arranged that a pair of opposite guide projections areprovided at the upper surface of the horizontal portion 160a of theinsulating cover 160, and that the card 170 is installed between theseguide projections so as to be reciprocatingly movable, whereby thecontacts are opened and closed.

Further, it may be arranged that a pair of elastic claws as shown inFIG. 8 are projectingly provided at the upper surface of the horizontalportion 160a of the insulating cover 160, and the card 170 is installedby pushing it from above to between these elastic claws, whereby thecard is restricted in position in the vertical direction as well as inthe horizontal direction.

Moreover, it may be arranged that one arch type projecting portion of agenerally U-shape in its front view as shown in FIG. 1 is formed at theupper surface of the horizontal portion 160a of the insulating cover160, or that a plurality of arch type projecting portions of a generallyU-shape in its front view as shown in FIG. 9 are formed in line at theupper surface of the horizontal portion 160a of the insulating cover160, in which arrangement the card is inserted into the projectingportion whereby it is restricted in position in the vertical directionas well as in the horizontal direction simultaneously.

Next, the card 170 may also be restricted in position not limitativelyvia the projecting portion provided at the upper surface of thehorizontal portion 160a of the insulating cover 160, but via one or aplurality of projecting portions provided at the ceiling surface of thecasing 180 or via one or a plurality of projecting portions orprojections provided, for example, at both the ceiling surface of thecasing 180 and the upper surface of the horizontal portion 160a of theinsulating cover 160 as shown in FIGS. 6 and 7.

However, the aforementioned guide projecting portion is preferablylocated in proximity to the contact mechanism 150 in order that theperformance characteristics are kept free from variations by reducingthe deflection of the card 170.

The second embodiment, as shown in FIG. 21, has an arrangement that,whereas the reciprocating movement of the card 170 is ensured by theprojecting portion 162 provided at the upper surface of the horizontalportion 160a of the insulating cover 160 in the aforementioned firstembodiment, the reciprocating movement of the card 170 is ensured by theprojecting portion 161 that restricts the card 170 in its position atthe time of return. The rest of the arrangement is similar to that ofthe first embodiment and therefore omitted in description.

The third embodiment, as shown in FIG. 22, is so arranged that the card170 may be assembled from above in a single direction.

More specifically, the long tongue 172 is extended horizontally from anend face central portion of the card 170, and the fitting projection 173is projectingly provided at the lower surface of its end portion, whilethe through hole 153c is provided at the elastic upper side portion 154bof the movable contact terminal 153.

With this arrangement, when the card 170 is pushed down from above, thefitting projection 173 of the card 170 is fitted to the through hole153c of the movable contact terminal 153 while the elastic engagementlegs 176, 176 of the card 170 are fitted to the cutouts 143, 143 of themoving core 140, whereby the card 170 is supported so as to bereciprocatingly movable. The rest of the arrangement is similar to thatof the first embodiment and therefore omitted in description.

The fourth embodiment, as shown in FIG. 23, is nearly the same as thefirst embodiment but differs in that the elastic base portion 154a ofthe elastic contact member 154 is caulked and fixed to a mountingportion 153d of the terminal portion 153b so that the pressing force ofthe card 170 acts on the caulking member as a shear force.

According to the present embodiment, even if the elastic base portion154a is formed of a thin-plate spring material, the portion fixed incaulking fashion becomes resistant to plastic deformation so that theelastic contact member 154 is free from rattling. Thus, the rockingfulcrum of the elastic vertical portion 154c will not move, offering anadvantage that stable performance characteristics are obtained.

The fifth embodiment, as shown in FIG. 24, has an arrangement that,whereas the aforementioned first embodiment has a normally-closed fixedcontact terminal 151, a dummy fixed contact terminal 155 withoutterminal portions is provided instead. This dummy fixed contact terminal155 has a dummy contact 155a formed by ejection process.

According to the present embodiment, by utilizing the other componentsexcept the dummy fixed contact terminal 155, there can be provided anelectromagnetic relay having only a normally-open fixed contact terminal152. Thus, an advantage that different types of electromagnetic relayscan be manufactured at a low parts count is offered.

INDUSTRIAL APPLICABILITY

The above described electromagnetic relays are not limited to thosehaving high insulating characteristic but can be applied to ordinaryelectromagnetic relays.

We claim:
 1. An electromagnetic relay which comprises: a base having an insulating wall of a generally U-shape in its plan view molded integrally at a generally center of a top surface of the base; an electromagnet block which is formed by winding a coil around an iron core and which is located at the top surface of the base so as to be surrounded by the insulating wall on one end side thereof; a contact mechanism located on one side of the top surface of the base partitioned by the insulating wall from one end side of the electromagnet block; an insulating cover covering an upper opening of the insulating wall; and a card for driving the contact mechanism by moving reciprocatingly and axially above the insulating cover as the electromagnet block is energized and de-energized.
 2. The electromagnetic relay according to claim 1, wherein the insulating cover has a generally "L"-shaped cross section, and covers at its vertical portion at least a central outer side face of the insulating wall so as to partition the electromagnet block and the contact mechanism from each other in a double structure.
 3. The electromagnetic relay according to claim 1 or 2, wherein a pair of projecting portions for sandwiching end portion side faces of the core that are exposed from the electromagnet block are provided at a bottom surface of the insulating cover.
 4. The electromagnetic relay according to any one of claims 1 or 2, wherein at least one projecting portion for ensuring the reciprocating movement of the card is provided in the top surface of the insulating cover so as to be in contact with the ceiling surface of a casing filled to the base.
 5. The electromagnetic relay according to any one of claims 1 or 2, wherein the electromagnet block is positioned by pressing it to the base with the insulating cover having at its top surface a projecting portion which comes into press contact with the ceiling surface of a casing fitted to the base.
 6. The electromagnetic relay according to any one of claims 1 or 2, wherein at least one guide projection for guiding the reciprocating movement of the card is provided at the top surface of the insulating cover.
 7. The electromagnetic relay according to any one of claims 1 or 2, wherein a projecting portion for restricting the card in its position by making contact with the card that has returned to its original position is provided at the top surface of the insulating cover. 